C₂ Symmetric Chiral Stationary Phases Based On Amino Acid Derivatives

Brush-type chiral stationary phases were widely used in the field of chiral analysis and preparation for its accessible raw materials,simple structure modification and predominant enantioseparation.Based on L-proline and other amino acid derivatives as chiral side chain,in this paper,a series of new type C2 symmetric chiral stationary phases were synthesized and evaluated by 31 kinds of chiral acidic,alkaline and neutral enantiomers for chiral separation.Compared with the single chain substituded,the C2 symmetric chiral stationary phase performed more outstanding with L-proline derivatives as chiral side chain,which indicate the superiority of the C2 symmetric structure.The important role of the hydrogen bonding interaction was revealed by investigating the type of polar additives in mobile phase in chiral recognition mechanism.The uncommon thermodynamic behaviors of different enantiomers on the C2 symmetric chiral stationary phase showed the special chiral recognition mechanism of this type as the temperature changed.The introduction of substitute group on the terminal phenyl moiety influenced the chiral separation of this type of chiral stationary phase to some extent.By changing the type of amino acids in the chiral side chain,the stationary phases derived from different chiral sources were compared to explore the change of chiral separation.The optimal separation were observed on the stationary phase that with L-proline derivatives as chiral side chain and phenyl endmost substituted.Chiral stationary phases based on phenylalanine and leucine expanded the ability of enantioseparation for this kind of chiral stationary phase.The aromatic properties of the endmost group on the chiral side chain was also investigated.Instead of amino acids as chiral source,the chiral stationary phases derived from the S-phenethylamine with different side chain lengths also had a good separation performance,which showed good prospects to the further development of this kind of stationary phase.